1. Technical Field
The present invention relates to an electrically actuated booster for use in an automotive brake mechanism or the like.
2. Description of the Related Art
There have heretofore been electrically actuated boosters that boost a pedal input with a electrically-operated actuator and output the boosted pedal input to a master cylinder. Among such electrically actuated boosters are those disclosed in the following patent documents.
Japanese Patent Application Publication No. Sho 60-92151 discloses an electrically actuated booster having an assist member (electromagnetic device) provided to assist the transmission of force from an input rod to a master cylinder. The electrically actuated booster further has a relative displacement sensor that detects a relative displacement between the input rod and the assist member. In the electrically actuated booster, the displacement of the assist member is controlled so that the input rod and the assist member are displaced together as one unit, i.e. the relative displacement detected by the relative displacement sensor is kept zero.
Japanese Patent Application Publication No. Hei 10-53122 discloses an electrically actuated booster in which an input rod that receives a pedal input and an assist member (piston shaft) are connected so that when the input rod is pressed, a controller applies force generated by an electric motor to the assist member, thereby displacing the assist member together with the input rod as one unit, and thus boosting the pedal input and outputting the boosted pedal input to a master cylinder.
Japanese Patent Application Publication No. Hei 10-138909 discloses an electrically actuated booster having an input rod that receives a pedal input and an assist member (main piston) operating in association with the input rod. One end of the assist member faces a pressure chamber of a master cylinder. When the input rod is pressed, a controller applies force generated by an electric motor to the assist member, thereby displacing the assist member, and thus boosting the pedal input and outputting the boosted pedal input to the master cylinder.